Calls have been made for an independent inquiry into the handling of sex assault allegations against a hospital worker who later killed a woman.
Nursing assistant Kris Wade admitted murdering neighbour Christine James in a sexually motivated attack in 2016.
The British Medical Association said a health board should not probe itself.
Dr David Bailey, the BMA's Welsh council deputy chairman, said:"We believe it is unacceptable for a health board to investigate serious concerns about itself.
"A desk top review which fails to speak to everyone involved in raising concerns is wholly insufficient and demonstrates a significant lack of transparency about the process.
"The review seems to absolve the health board from any responsibility for not acting sooner, this is simply unacceptable."
The review concluded it did not believe the killing could have been predicted.
'Number of issues'
Wade worked in the learning and disabilities directorate based at Rowan House, Cardiff, when three separate allegations were made, between July 2010 and December 2011, by former patients.
They were referred to South Wales Police but no criminal charges were brought.
When Wade was arrested for murder in March 2016, he was already suspended by ABMU while the health board held a disciplinary process over the sexual assault allegations.
He was later sacked.Image copyright Google Image caption
The health board report concluded:"The review concludes there were a number of issues relating to health board processes and responses to the allegations that needed to be improved."
"It does not however consider that the issues identified could have otherwise predicted or prevented Mr Wade's future conduct and behaviour outside of his employment," it added.
"Despite police being informed of all sexual abuse allegations, the review concluded that the health board's internal reporting procedures had not been followed robustly enough.
"This did not relate to any deliberate attempt to conceal the allegations, but was more a reflection of a wider culture within certain healthcare settings to base actions on the believability of patients, rather than the use of safeguarding processes."
The report also looked at whether there were potential conflicts of interest between Wade and his father, who was the board's mental health and learning disabilities clinical service director, but has since retired.
It found Wade's father took no part in investigating any allegations against his son, nor was there any written evidence suggesting he "overtly influenced" the board's investigations.
The health board said South Wales Police confirmed Wade did not have a criminal record when he was first employed.
A spokeswoman added:"ABMU health board is finalising a new policy which will provide advice and guidance to managers when dealing with matters of HR when friends and family are involved.
"This will ensure transparency where relationships are identified within the same service.
"Other recent changes include the introduction in 2015 by ABMU of a serious incident investigation team to monitor serious incidents and work proactively with managers, and in some cases support an independent investigation."
'Laissez faire attitude'
A Welsh Government spokesman said:"We expect health boards to robustly investigate any serious allegations made against NHS staff, and to take appropriate action if necessary.
"In addition, there are clear national policies in place which set out the process for staff who wish to raise concerns.
"Health boards are expected to have robust and effective processes and governance arrangements in place to handle any concerns raised."
Welsh Conservatives leader Andrew RT Davies has also called for an independent inquiry.
"A laissez faire attitude to safeguarding and a culture of stubborn unwilling to take seriously the testimony of patients and staff members enabled Kris Wade to act out his urges with impunity for far too long," he said.
Bethan Jenkins, Plaid Cymru AM for South Wales West, echoed the call and said she wanted the assembly to be recalled for the issue to be debated....
- ^ admitted murdering neighbour Christine James in a sexually motivated attack (www.bbc.co.uk)
- ^ internal report (www.wales.nhs.uk)